JPS59635A - Power sensor - Google Patents

Abstract

PURPOSE:To stabilize a signal and to obtain an inexpensive power sensor, by using a photoelastic material to form the sensor and detecting a stress condition of the material by utilizing photoelastic phenomena. CONSTITUTION:A sensor is formed by a photoelastic material 9 such as glass, bakelite, epoxy resin etc. and light from a light source 6 polarized by a polarizing board 7 is introduced into a measuring place of the sensor by an optical fiber 8. The intensity of transmitted light of the polarized light is varied by photoelastic phenomena by a stress condition of the material. Said transmitted light is introduced into a photodetecting element 11 by an optical fiber 10. Striped pattern of light and darkness appears in the material by increasing the stress and new pattern appears together with the alteration of the stress. Accordingly, pulse input appears successively in the fiber 10 and is integrated by a counter 12 and the stress is found. For this reason, the signal is stabilized and the inexpensive power sensor is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a force sensor that utilizes a photoelastic phenomenon.

Conventional force sensors use a resistance wire strain gauge to detect the strain that occurs in the sensitive part, amplify the amount of strain, convert the analog value into digital data, input it into a computer, and calculate the force component. This method has the following drawbacks:

(1) The output of the strain gauge is unstable.

(2) Amplifiers are expensive.

(3) A/D converters are expensive.

The present invention aims to provide the same effect at a lower cost by utilizing the photoelastic phenomenon in place of the conventionally widely used knife centimeter using a strain gauge.

The present invention will be specifically explained below based on the drawings.

The construction shown in Figure 1 is made of sea urchin, glass, and Bakelite.

When polarized light 2 is transmitted through a photoelastic material 1 such as an epoxy resin, the original intensity of the transmitted light changes depending on the stress state of the material. The intensity of transmitted light is i, and the incident polarized light is Asinwt.
, the phase difference between the ordinary light and the extraordinary polarized light is a.

If the inclination between the incident light and the principal stress plane is θ, then a linear equation holds true.

Therefore.

It becomes l-0 at δ-2nπ.

That is, from K, which measures the intensity of transmitted light.

It can refer to the state of stress that occurs in a material.

FIG. 2 shows an external appearance of an embodiment of the present invention, and FIG. 3 shows a block diagram thereof.

The light that exits the light source 6 is polarized by a polarizing plate.

This light is guided to the original fiber by 9 and 1 to each stress measurement point. Thereupon, the source that has passed through the photoelastic material 9 is guided back into the optical fiber to the edge receiving element 11 through the casing.

The shape of the photoelastic material and the location where stress is measured are determined in accordance with the specifications of the optical sensor.

Now, the case where a load is applied to the centerpiece shown in FIG. 1 will be explained with reference to FIG. 3. As the stress in the material becomes larger δ, the value of L81n27-, which is the principal stress difference of equation 1 (υ), changes, and a pattern of light and dark stripes appears in the material.

First, the hailstones are called zero-order islands, and the light-receiving optical fiber 10 is placed near the place where the hailstones occur.

As the stress increases, f'L and Ll move, and new stripes are created one after another.

Looking at this n from the output of the light receiving element, it is equivalent to inputting pulses one after another for one hour as shown in FIG. 1st
The stress is determined by integrating the number of pulses of Lori on the counter 2 in the figure. Even when reducing the load, do bright and dark stripes occur in the same way?Is it possible to install two sets of receiving source fibers close to each other for one foot measurement point, detect one movement of the bright and dark stripes, and increase or decrease the counter? and deal with it.

One of the above-mentioned features is that the sword sensor according to the present invention does not use strain gauges, so the signal can be stabilized, reliability is improved, and an amplifier and A/Df converter are not required, resulting in low cost. It has the effect of making it possible to

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of the principle of photoelasticity used in the present invention. FIG. 2 is an external view of one embodiment of the present invention, FIG. 3 is a block diagram thereof, FIG. 4 is an explanatory diagram showing the action of the original elastic material, and FIG. 5 is an output waveform diagram of the light receiving element. 6... Light source, 7... Polarizing plate, 8... Original fiber, 9... Photoelastic material, 10... Optical fiber, 11
... Light receiving element, 12... Counter. Agent Patent Attorney Usui Li Xi Ambiguous Leopard Cheating Talent 4t! 1. Nawsai 5.

Claims (1)

[Claims] A force sensor characterized by using a light source, a polarizing plate, an original fiber, a light receiver, and a photoelastic material.